1. Field of the Invention
The present invention relates to underground stations and more particularly to an underground station having an access cover with a versatile attaching frame.
2. Description of the Prior Art
Underground stations such as pumping stations require access openings which are usually closed by access covers formed from a strong rigid material such as steel. The more sophisticated covers are mounted in a welded frame which is cast into a concrete slab formed about the access opening. The access covers are mass produced and mounted in the frame without regard to the specific requirements of a particular pumping station. Various accessories such as guide holders, cable holders, chain hooks, ladders, fluid level sensors and power outlets are commonly mounted to the access cover frame. The frame is provided with predrilled mounting holes disposed in predetermined locations for the purpose of mounting these accessories. Threaded nuts are usually welded on the rear side of the frame in alignment with predrilled holes for receiving accessory mounting bolts.
Experience has shown that in many instances the nuts are misaligned and do not coincide with the predrilled holes so that the accessory mounting bolts cannnot be threaded into the nuts. Unfortunately, this condition is usually discovered after the frame is cast into the concrete slab and the problem may not be corrected without breaking the concrete away to gain access to the rear side of the mounting frame. This has proven to be an expensive and time consuming operation in addition to substantially degrading the overall appearance of the pumping station after the concrete is repaired.
The frames are mass produced with a number of mounting holes disposed in predetermined locations without regard to the preferred requirements of a particular pumping station. The prior art access covers lacked the versatility that is desired for simplifying installation and obtaining the most efficient station installation. The hinges were attached to the frame on a predetermined side without regard to the pumping station location which resulted in problems if an obstruction happened to be located in the access area.
To provide the most efficient pumping station, the previously mentioned accessories should be mounted in locations that can be determined only after the pumping station locations are completely surveyed. The preferred locations for the junction boxes for power cables and sensor cables will be dictated by the location of the power source at the station. The pumps used in the station usually require level sensors that are preferably mounted in an area remote from the fluid inlet where turbulence is usually experienced. Thus, it is important to have the flexibility to be able to locate the sensors in the area of least turbulence. The pumps themselves should be mounted in a location convenient to the discharge outlet.
Thus, the prior art access covers not only resulted in problems with misaligned mounting holes, they also lacked the necessary flexibility for proper installation of an efficient pumping station.